Wednesday, November 7, 2012

Channelized impact melt at Egede A

Impact melt, from nearby Egede A crater, formed channels as it flowed one
kilometer down slope. Cracks in the melt probably formed as a result of
cooling and inflation. Half-kilometer-wide field of view from LROC Narrow Angle Camera (NAC) frame M175204950LE, LRO orbit 10954, November 6, 2011; resolution 0.43 meters, in the original, an an incidence angle 63.49° from 29.54 kilometers
[NASA/GSFC/Arizona State University].

Dew EnnsLROC News System

Impact melt creates spectacular morphologies on the Moon. Sometimes melt pools into large ponds, sometimes melt cascades down crater terraces, and sometimes melt forms channelized flows. The Egede A impact melt flows (as well as numerousotherflows) are channelized with levees at their margins. Are there any analogues for channelized impact melt flows on Earth?

Yes! Levees occur naturally in terrestrial lava flows and develop as the
edges of a lava flow cool and solidify. The lava flow can channelize
with the levees help and make itself more thermally efficient. The
levees allow the flow to travel farther from its source by slowing the
cooling.

LROC Wide Angle Camera context image of the LROC Featured Image released November 6, 2012 (located in the white box).
Egede A is a 12.3 km crater at 51.57° N, 10.51 E, northeast of the Vallis Alpes. Monochrome (604 nm) mosaic stitched from subsequent observation opportunities in orbits
3132 and 3134, March 2, 2010; from LROC WAC
observations M122130239C and M122143802C. Resolution average 59.9 meters per pixel from 42 kilometers[NASA/GSFC/Arizona
State University]. [NASA/GSFC/Arizona State University].

The morphological similarity between lava flows and impact melt implies they behave in a similar manner and have similar properties (temperature and viscosity).

In Mare Frigoris, on the entrance to Valles Alps opposite from Mare Imbrium, Egede A is easy to find through a modest telescope, Google Earth - Moon. True color still from a presentation prepared by the NASA Science Visualization Studio at Goddard Space Flight Center [NASA/GSFC/SVS]